Process for the recovery of manganese chloride from a sartan-biphenyl catalyst

Abstract

This invention relates to a method for recovering manganese chloride from a sartan-biphenyl catalyst, using manganese hydroxide obtained after manganese-magnesium separation as raw material, comprising the following steps: S1, heating and impurity removal; S2, slurry preparation; S3, reduction reaction; S4, neutralization and acid removal: adding manganese carbonate to the reduced system to neutralize excess hydrochloric acid, adjusting the overall pH to 5-7, and filtering to remove trace insoluble impurities; S5, concentration and distillation: transferring the filtrate from S4 to a distillation kettle, and distilling under reduced pressure with stirring at a vacuum degree ≤ -0.05 MPa, concentrating to a Baume degree of 52-53; S6, crystallization and mother liquor recycling: cooling the concentrated liquid from S5 to 10-20℃ for crystallization, and filtering to obtain manganese chloride tetrahydrate crystals; S7, high-temperature drying to prepare anhydrous manganese chloride. This invention significantly reduces the amount of fresh manganese chloride raw material purchased, achieving solid waste reduction and resource recycling, and meeting the requirements of green chemical production.

Description

Technical Field

[0001] This invention relates to the field of chemical resource recovery technology, and in particular to a method for recovering manganese chloride from a sartan biphenyl catalyst. Background Technology

[0002] In the organic synthesis of sartan-biphenyl, manganese chloride is often used as a dedicated catalyst for Grignard reagent carbon-carbon bond reactions, catalyzing reactions such as acylation, coupling, and carbon metallization. The production process continuously generates large quantities of mixed process waste liquid containing manganese and magnesium chloride. If this waste liquid is directly discharged, the manganese in it will seep into the soil and water, causing ecological pollution; manganese accumulation in plants and animals can lead to poisoning; and long-term exposure to excessive manganese can cause irreversible damage to the central nervous system in humans, placing immense pressure on environmental disposal. Therefore, the industry generally adopts a manganese-magnesium separation process to pretreat the waste liquid, obtaining manganese metahydroxide as a solid precipitate after separation, thereby reducing the manganese content of the waste liquid.

[0003] Chemical precipitation separation methods often use sodium fluoride to precipitate magnesium ions. Although this can achieve the separation of manganese and magnesium, it introduces sodium ion impurities into the system, requiring secondary purification of the manganese products. Furthermore, fluoride salts can easily cause secondary pollution. Solvent extraction methods for separating manganese and magnesium are still in the laboratory research and development stage. They have low separation efficiency and lack mature industrial processes, making them unsuitable for large-scale application. Electrolysis methods rely on anodic oxidation to precipitate manganese dioxide and recover manganese. However, they suffer from high equipment investment, high energy consumption, and low overall processing efficiency, making them unsuitable for mass production conditions. Existing manganese-magnesium separation processes only separate magnesium and manganese into two phases, achieving only the harmless treatment and reduction of waste liquid. They do not design a complete regeneration and recycling route for the separated manganese hydroxide precipitate, resulting in the inability to achieve a closed-loop recycling of manganese resources and high raw material losses and costs. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method for recovering manganese chloride from a sartan biphenyl catalyst.

[0005] A method for recovering manganese chloride from a sartan biphenyl catalyst, using manganese hydroxide obtained after manganese-magnesium separation as raw material, includes the following steps: S1. Heating and removing impurities: Add manganese hydroxide and water to the reactor, stir and heat to 60-80℃, add dilute hydrochloric acid dropwise to remove impurities, control the system temperature to not exceed 80℃ throughout the process, and adjust the pH value of the system to 3-4; pump the material in the reactor to filter, collect the filter cake and rinse the filter cake. S2. Slurry preparation: The rinsed filter cake is put into the reaction vessel, water is added and stirred, and hydrochloric acid is added dropwise at room temperature to adjust the pH value of the slurry to 1-2, so as to obtain black manganese-based slurry. S3. Reduction reaction: Add hydrochloric acid and oxalic acid to the reactor beforehand and stir evenly. Control the temperature at 50-80℃ and slowly add the black manganese-based slurry obtained in step S2 until the material in the reactor turns dark and the reduction reaction is completed. S4. Neutralization and deacidification: Add manganese carbonate to the reduced system to neutralize excess hydrochloric acid, adjust the overall pH value to 5-7, and filter to remove trace amounts of insoluble impurities in the system. S5. Concentration and distillation: Transfer the filtrate from S4 into a distillation kettle and distill under reduced pressure with stirring under vacuum conditions of ≤-0.05MPa until the material Baumé degree is 52-53. S6. Crystallization and Mother Liquor Recycling: Cool the concentrated liquid in S5 to 10-20℃ to crystallize, filter and separate to obtain manganese chloride tetrahydrate crystals, and recycle the filtrate generated from the crystallization separation to the distillation process of S5. S7. Preparation of anhydrous manganese chloride by high-temperature drying: The manganese chloride tetrahydrate filter cake obtained in S6 is dried at 220℃ for 6 hours to obtain the anhydrous manganese chloride product.

[0006] Preferably, the mass concentration of the dilute hydrochloric acid used for impurity removal in S1 is 8%-10%.

[0007] Preferably, the mass concentration of hydrochloric acid in S2 is 30%-32%.

[0008] Preferably, the S3 reduction reaction only produces carbon dioxide gas which is discharged and does not introduce other impurity ions into the system, thus producing high-purity manganese chloride.

[0009] Preferably, step S4 involves first adding manganese carbonate to the reduced system to neutralize excess hydrochloric acid, neutralizing the system to a pH of 2-3, then continuing to add manganese carbonate to adjust the overall pH to 5-7, and finally filtering to remove trace amounts of insoluble impurities from the system.

[0010] Preferably, step S5 involves distilling to a Baume degree of 52-53. At this concentration, the material will not crystallize at the distillation completion temperature, and impurities from the crystallized material will not precipitate out, resulting in a considerable yield.

[0011] Preferably, the crystallized filtrate in S6 is distilled under reduced pressure with stirring under vacuum conditions of ≤-0.05MPa, concentrated to a Baume degree of 52-53, and allowed to stand for static crystallization for 3-5 days. The upper mother liquor is returned for re-oxidation, and the lower crystals are dissolved in water and then filtered together with S4.

[0012] This invention addresses the complete resource recovery of manganese hydroxide precipitate generated after manganese-magnesium separation, converting the waste into reusable manganese chloride tetrahydrate and anhydrous manganese chloride products. The reaction equations are as follows: MnO(OH)2+2HCl+HCOOH→MnCl2+CO2↑+4H2O It is reused in the catalytic synthesis process of sartan biphenyl, which significantly reduces the amount of fresh manganese chloride raw material purchased, achieves solid waste reduction and resource recycling, and meets the requirements of green chemical production.

[0013] This invention uses oxalic acid or formic acid as a reducing agent. After the reaction, only carbon dioxide gas is generated and directly discharged from the system. No foreign impurity ions such as sodium and fluorine are introduced. No additional deep impurity removal process is required. Finally, high-purity manganese chloride is obtained, which meets the standard for recycling catalytic reactions.

[0014] This invention removes impurities such as magnesium and trace heavy metals from the system step by step by controlling the pH of the impurity removal process, the pH of the slurry, the pH of the neutralization process, the reduction temperature, the distillation vacuum, and the crystallization and drying conditions. Solid-liquid separation and mother liquor recycling further improve the total recovery rate of manganese. The process is highly stable and suitable for continuous industrial production. All filtrate generated in the crystallization process is recycled to the vacuum distillation section for repeated concentration, reducing wastewater production, lowering the load on end-of-pipe wastewater treatment, and reducing environmental treatment costs and pollution pressure.

[0015] This invention can be completed using conventional chemical equipment such as reaction kettles, filters, and vacuum distillation, without the need for high-cost specialized electrolysis and extraction devices. The reaction conditions are mild, without harsh high-temperature or high-pressure conditions, resulting in low overall energy consumption and a low barrier to industrialization. This invention enables on-site recycling and regeneration of manganese-containing waste, avoiding manganese pollution of soil and water caused by the stockpiling and discharge of manganese hydroxide solid waste, and eliminating manganese-induced poisoning in plants and animals and damage to the human nervous system. The entire production process is more environmentally friendly and safer. Attached Figure Description

[0016] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0017] Reference Figure 1 The present invention will be further explained below with reference to specific embodiments.

[0018] Example 1: A method for recovering manganese chloride from a sartan biphenyl catalyst, using manganese metahydride obtained by a company from separating manganese from magnesium chloride as raw material, includes the following steps: S1. Heating and removing impurities: Add manganese hydroxide and water to the reactor, stir and heat to 60-80°C, add 8-10% dilute hydrochloric acid to remove impurities, control the system temperature to not exceed 80°C throughout the process, and adjust the pH value of the system to 3-4; pump the material in the reactor to filter, collect the filter cake and rinse the filter cake. S2. Slurry preparation: The rinsed filter cake is put into the reaction vessel, water is added and stirred. Hydrochloric acid with a mass concentration of 30% is added dropwise at room temperature to adjust the pH value of the slurry to 1-2, and a black manganese-based slurry is obtained. S3. Reduction reaction: Add hydrochloric acid and oxalic acid to the reactor beforehand and stir evenly. Control the temperature at 50-80℃ and slowly add the black manganese-based slurry obtained in step S2 until the material in the reactor turns dark and the reduction reaction is completed. S4. Neutralization and deacidification: First, add manganese carbonate to the reduced system to neutralize the excess hydrochloric acid. The system is first neutralized to pH 2-3. Then, continue to add manganese carbonate to adjust the overall pH to 5-7. Filter to remove trace amounts of insoluble impurities in the system. S5. Concentration and distillation: Transfer the filtrate from S4 into a distillation kettle and distill under reduced pressure with stirring under vacuum conditions of ≤-0.05MPa until the material Baumé degree is 52-53. S6. Crystallization and Mother Liquor Circulation: Cool the concentrated liquid in S5 to 10-20℃ for cooling and crystallization, and filter to obtain manganese chloride tetrahydrate crystals; distill the crystallization mother liquor under reduced pressure with stirring under vacuum conditions of ≤-0.05MPa, concentrate it to a Baume degree of 52-53, let it stand for static crystallization for 3-5 days, return the upper layer of mother liquor for re-oxidation, dissolve the lower layer of crystals in water, and filter it together with S4; S7. Preparation of anhydrous manganese chloride by high-temperature drying: The manganese chloride tetrahydrate filter cake obtained in S6 is dried at 220℃ for 6 hours to obtain the anhydrous manganese chloride product.

[0019] Example 2, a method for recovering manganese chloride from a sartan biphenyl catalyst, using manganese metahydride obtained by a company from separating manganese from magnesium chloride as raw material, includes the following steps: S1. Heating and removing impurities: Add manganese hydroxide and water to the reactor, stir and heat to 30-50°C, add 8-10% dilute hydrochloric acid to remove impurities, control the system temperature to not exceed 60°C throughout the process, and adjust the pH value of the system to 4-5; pump the material in the reactor to filter, collect the filter cake and rinse the filter cake. S2. Slurry preparation: The rinsed filter cake is put into the reaction vessel, water is added and stirred. Hydrochloric acid with a mass concentration of 30% is added dropwise at room temperature to adjust the pH value of the slurry to 1-2, and a black manganese-based slurry is obtained. S3. Reduction reaction: Add hydrochloric acid and oxalic acid to the reactor beforehand and stir evenly. Control the temperature at 50-80℃ and slowly add the black manganese-based slurry obtained in step S2 until the material in the reactor turns dark and the reduction reaction is completed. S4. Neutralization and deacidification: First, add manganese carbonate to the reduced system to neutralize the excess hydrochloric acid. The system is first neutralized to pH 2-3. Then, continue to add manganese carbonate to adjust the overall pH to 5-7. Filter to remove trace amounts of insoluble impurities in the system. S5. Concentration and distillation: Transfer the filtrate from S4 into a distillation kettle and distill under reduced pressure with stirring under vacuum conditions of ≤-0.05MPa until the material Baumé degree is 52-53. S6. Crystallization and Mother Liquor Circulation: Cool the concentrated liquid in S5 to 10-20℃ for cooling and crystallization, and filter to obtain manganese chloride tetrahydrate crystals; distill the crystallization mother liquor under reduced pressure with stirring under vacuum conditions of ≤-0.05MPa, concentrate it to a Baume degree of 52-53, let it stand for static crystallization for 3-5 days, return the upper layer of mother liquor for re-oxidation, dissolve the lower layer of crystals in water, and filter it together with S4; S7. Preparation of anhydrous manganese chloride by high-temperature drying: The manganese chloride tetrahydrate filter cake obtained in S6 is dried at 220℃ for 6 hours to obtain the anhydrous manganese chloride product.

[0020] Example 3, a method for recovering manganese chloride from a sartan biphenyl catalyst, using manganese metahydride obtained by a company from separating manganese from magnesium chloride as raw material, includes the following steps: S1. Heating and impurity removal: Add manganese hydroxide and water to the reactor, stir and heat to 60-80℃, add 30% dilute hydrochloric acid to remove impurities, control the system temperature to not exceed 80℃ throughout the process, and adjust the pH value of the system to 2-3; pump the material in the reactor to filter, collect the filter cake and rinse the filter cake. S2. Slurry preparation: The rinsed filter cake is put into the reaction vessel, water is added and stirred. Hydrochloric acid with a mass concentration of 30% is added dropwise at room temperature to adjust the pH value of the slurry to 1-2, and a black manganese-based slurry is obtained. S3. Reduction reaction: Add hydrochloric acid and oxalic acid to the reactor beforehand and stir evenly. Control the temperature at 50-80℃ and slowly add the black manganese-based slurry obtained in step S2 until the material in the reactor turns dark and the reduction reaction is completed. S4. Neutralization and deacidification: First, add manganese carbonate to the reduced system to neutralize the excess hydrochloric acid. The system is first neutralized to pH 2-3. Then, continue to add manganese carbonate to adjust the overall pH to 5-7. Filter to remove trace amounts of insoluble impurities in the system. S5. Concentration and distillation: Transfer the filtrate from S4 into a distillation kettle and distill under reduced pressure with stirring under vacuum conditions of ≤-0.05MPa until the material Baumé degree is 52-53. S6. Crystallization and Mother Liquor Circulation: Cool the concentrated liquid in S5 to 10-20℃ for cooling and crystallization, and filter to obtain manganese chloride tetrahydrate crystals; distill the crystallization mother liquor under reduced pressure with stirring under vacuum conditions of ≤-0.05MPa, concentrate it to a Baume degree of 52-53, let it stand for static crystallization for 3-5 days, return the upper layer of mother liquor for re-oxidation, dissolve the lower layer of crystals in water, and filter it together with S4; S7. Preparation of anhydrous manganese chloride by high-temperature drying: The manganese chloride tetrahydrate filter cake obtained in S6 is dried at 220℃ for 6 hours to obtain the anhydrous manganese chloride product.

[0021] Example 4, a method for recovering manganese chloride from a sartan biphenyl catalyst, using manganese metahydride obtained by a company from separating manganese from magnesium chloride as raw material, includes the following steps: S1. Heating and removing impurities: Add manganese hydroxide and water to the reactor, stir and heat to 60-80°C, add 8-10% dilute hydrochloric acid to remove impurities, control the system temperature to not exceed 80°C throughout the process, and adjust the pH value of the system to 3-4; pump the material in the reactor to filter, collect the filter cake and rinse the filter cake. S2. Slurry preparation: The rinsed filter cake is put into the reaction vessel, water is added and stirred. Hydrochloric acid with a mass concentration of 30% is added dropwise at room temperature to adjust the pH value of the slurry to 1-2, and a black manganese-based slurry is obtained. S3. Reduction reaction: Add hydrochloric acid and oxalic acid to the reactor beforehand and stir evenly. Control the temperature at 50-80℃ and slowly add the black manganese-based slurry obtained in step S2 until the material in the reactor turns dark and the reduction reaction is completed. S4. Neutralization and deacidification: First, add manganese carbonate to the reduced system to neutralize the excess hydrochloric acid. The system is first neutralized to pH 2-3. Then, continue to add manganese carbonate to adjust the overall pH to 5-7. Filter to remove trace amounts of insoluble impurities in the system. S5. Concentration and distillation: Transfer the filtrate from S4 into a distillation kettle and distill under reduced pressure with stirring under vacuum conditions of ≤-0.05MPa until the material Baumé degree is 54-56. S6. Crystallization and Mother Liquor Circulation: Cool the concentrated liquid in S5 to 20-30℃ for cooling and crystallization, and filter to obtain manganese chloride tetrahydrate crystals; distill the crystallization mother liquor under reduced pressure with stirring under vacuum conditions of ≤-0.05MPa, concentrate it to a Baume degree of 52-53, let it stand for static crystallization for 3-5 days, return the upper layer of mother liquor for re-oxidation, dissolve the lower layer of crystals in water, and filter it together with S4; S7. Preparation of anhydrous manganese chloride by high-temperature drying: The manganese chloride tetrahydrate filter cake obtained in S6 is dried at 220℃ for 6 hours to obtain the anhydrous manganese chloride product.

[0022] Example 5, a method for recovering manganese chloride from a sartan biphenyl catalyst, using manganese metahydride obtained by a company from separating manganese from magnesium chloride as raw material, includes the following steps: S1. Heating and removing impurities: Add manganese hydroxide and water to the reactor, stir and heat to 60-80°C, add 8-10% dilute hydrochloric acid to remove impurities, control the system temperature to not exceed 80°C throughout the process, and adjust the pH value of the system to 3-4; pump the material in the reactor to filter, collect the filter cake and rinse the filter cake. S2. Slurry preparation: The rinsed filter cake is put into the reaction vessel, water is added and stirred. Hydrochloric acid with a mass concentration of 30% is added dropwise at room temperature to adjust the pH value of the slurry to 1-2, and a black manganese-based slurry is obtained. S3. Reduction reaction: Add hydrochloric acid and oxalic acid to the reactor beforehand and stir evenly. Control the temperature at 50-80℃ and slowly add the black manganese-based slurry obtained in step S2 until the material in the reactor turns dark and the reduction reaction is completed. S4. Neutralization and deacidification: First, add manganese carbonate to the reduced system to neutralize the excess hydrochloric acid. The system is first neutralized to pH 2-3. Then, continue to add manganese carbonate to adjust the overall pH to 5-7. Filter to remove trace amounts of insoluble impurities in the system. S5. Concentration and distillation: Transfer the filtrate from S4 into a distillation kettle and distill under reduced pressure with stirring under vacuum conditions of ≤-0.05MPa until the material Baumé degree is 52-53. S6. Crystallization: Cool the concentrated solution in S5 to 10-20℃ to crystallize, filter and separate to obtain manganese chloride tetrahydrate crystals, and discard the filtrate for re-oxidation. S7. Preparation of anhydrous manganese chloride by high-temperature drying: The manganese chloride tetrahydrate filter cake obtained in S6 is dried at 220℃ for 6 hours to obtain the anhydrous manganese chloride product.

[0023] Example 6, a method for recovering manganese chloride from a sartan biphenyl catalyst, using manganese metahydride obtained by a company from separating manganese from magnesium chloride as raw material, includes the following steps: S1. Heating and removing impurities: Add manganese hydroxide and water to the reactor, stir and heat to 60-80°C, add 8-10% dilute hydrochloric acid to remove impurities, control the system temperature to not exceed 80°C throughout the process, and adjust the pH value of the system to 3-4; pump the material in the reactor to filter, collect the filter cake and rinse the filter cake. S2. Slurry preparation: The rinsed filter cake is put into the reaction vessel, water is added and stirred. Hydrochloric acid with a mass concentration of 30% is added dropwise at room temperature to adjust the pH value of the slurry to 2-3, and a black manganese-based slurry is obtained. S3. Reduction reaction: Add hydrochloric acid and oxalic acid to the reactor beforehand and stir evenly. Control the temperature at 50-80℃ and slowly add the black manganese-based slurry obtained in step S2 until the material in the reactor turns dark and the reduction reaction is completed. S4. Neutralization and deacidification: A large amount of oxalic acid has not been completely reacted. Excess hydrochloric acid needs to be added to completely react the oxalic acid. Then, manganese carbonate is added to the reduced system to neutralize the excess hydrochloric acid. The system is first neutralized to pH 2-3. Then, manganese carbonate is added to adjust the overall pH to 5-7. The system is then filtered to remove trace amounts of insoluble impurities. S5. Concentration and distillation: Transfer the filtrate from S4 into a distillation kettle and distill under reduced pressure with stirring under vacuum conditions of ≤-0.05MPa until the material Baumé degree is 52-53. S6. Crystallization and Mother Liquor Circulation: Cool the concentrated liquid in S5 to 10-20℃ for cooling and crystallization, and filter to obtain manganese chloride tetrahydrate crystals; distill the crystallization mother liquor under reduced pressure with stirring under vacuum conditions of ≤-0.05MPa, concentrate it to a Baume degree of 52-53, let it stand for static crystallization for 3-5 days, return the upper layer of mother liquor for re-oxidation, dissolve the lower layer of crystals in water, and filter it together with S4; S7. Preparation of anhydrous manganese chloride by high-temperature drying: The manganese chloride tetrahydrate filter cake obtained in S6 is dried at 220℃ for 6 hours to obtain the anhydrous manganese chloride product.

[0024] Comparative Example 1, a method for recovering manganese chloride from a sartan biphenyl catalyst, comprising the following steps: S1. Collect the mixed waste liquid containing manganese and magnesium, add sodium fluoride, magnesium ions will form magnesium fluoride precipitate, and filter to remove magnesium impurities; S2. Manganese ions in the filtrate are oxidized by air and oxygen to form a solid precipitate of manganese hydroxide, which is then collected as manganese mud by pressure filtration. Manganese sludge disposal can be carried out in two extensive ways: S21. Hazardous waste is outsourced for disposal and directly transported to landfills without any resource recovery. S22, simple hydrochloric acid resolution, no graded pH purification, no temperature-controlled reduction, direct concentration and crystallization.

[0025] Comparative Example 2, a method for recovering manganese chloride from a sartan biphenyl catalyst, comprising the following steps: S1. A phosphorus-based extractant is used to extract the manganese-magnesium mixture in stages, enriching manganese ions in the organic phase and magnesium chloride in the aqueous phase. S2. The organic phase is back-extracted with dilute hydrochloric acid to obtain a manganese salt solution, which is then oxidized and precipitated to obtain manganese hydroxide. S3, manganese mud is directly concentrated and crystallized after simple acid washing.

[0026] The finished products prepared in Examples 1-6 and Comparative Examples 1-2 were tested, and the results of the total recovery rate of manganese and the purity of manganese chloride are shown in the table below: Example 1 78.51% 99.30% Example 2 82.03% 97.53% Example 3 59.18% 99.56% Example 4 79.15% 98.03% The material is difficult to dry Example 5 65.55% 99.49% Example 6 78.52% 99.10% The number of steps increases, making the operation more difficult. Comparative Example 1 62.05% 82.46% Comparative Example 2 73.13% 88.32% From the above conclusions, it is known that Examples 1, 2, 3, 4, and 6 all included mother liquor circulation, but compared with Comparative Example 5, there was no mother liquor circulation, resulting in a low manganese recovery rate. In Example 3, 30% dilute hydrochloric acid was added dropwise in the initial S1 to remove impurities, but the hydrochloric acid concentration was too high, leading to a low manganese recovery rate. In Example 6, due to a large amount of unreacted oxalic acid in S3, an excessive amount of hydrochloric acid needed to be added to completely react the oxalic acid, increasing the operational difficulty. In Example 4, the material was concentrated to a Baume degree of 54-56, and the concentrate was cooled to 20-30°C for crystallization, but there was a problem that the material was difficult to dry, resulting in a low manganese recovery rate. Comparative Examples 1-2 used existing technology for manganese recovery, and their manganese recovery rate and manganese chloride purity were lower than those of Examples 1 and 2. Therefore, Examples 1 and 2 are confirmed as the optimal embodiments of the present invention.

[0027] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for recovering manganese chloride from a sartan biphenyl catalyst, characterized in that, Using manganese hydroxide obtained after manganese-magnesium separation as raw material, the process includes the following steps: S1. Heating and removing impurities: Add manganese hydroxide and water to the reactor, stir and heat to 60-80℃, add dilute hydrochloric acid dropwise to remove impurities, control the system temperature to not exceed 80℃ throughout the process, and adjust the pH value of the system to 3-4; pump the material in the reactor to filter, collect the filter cake and rinse the filter cake. S2. Slurry preparation: The rinsed filter cake is put into the reaction vessel, water is added and stirred, and hydrochloric acid is added dropwise at room temperature to adjust the pH value of the slurry to 1-2, so as to obtain black manganese-based slurry. S3. Reduction reaction: Add hydrochloric acid and oxalic acid to the reactor beforehand and stir evenly. Control the temperature at 50-80℃ and slowly add the black manganese-based slurry obtained in step S2 until the material in the reactor turns dark and the reduction reaction is completed. S4. Neutralization and deacidification: Add manganese carbonate to the reduced system to neutralize excess hydrochloric acid, adjust the overall pH value to 5-7, and filter to remove trace amounts of insoluble impurities in the system. S5. Concentration and distillation: Transfer the filtrate from S4 into a distillation kettle and distill under reduced pressure with stirring under vacuum conditions of ≤-0.05MPa until the material Baumé degree is 52-53. S6. Crystallization and Mother Liquor Recycling: Cool the concentrated liquid in S5 to 10-20℃ to crystallize, filter and separate to obtain manganese chloride tetrahydrate crystals, and recycle the filtrate generated from the crystallization separation to the distillation process of S5. S7. Preparation of anhydrous manganese chloride by high-temperature drying: The manganese chloride tetrahydrate filter cake obtained in S6 is dried at 220℃ for 6 hours to obtain the anhydrous manganese chloride product.

2. The method for recovering manganese chloride from a sartan biphenyl catalyst according to claim 1, characterized in that, The mass concentration of dilute hydrochloric acid used to remove impurities in S1 is 8%-10%.

3. The method for recovering manganese chloride from a sartan biphenyl catalyst according to claim 1, characterized in that, The mass concentration of hydrochloric acid in S2 is 30%-32%.

4. The method for recovering manganese chloride from a sartan biphenyl catalyst according to claim 1, characterized in that, The S3 reduction reaction only produces carbon dioxide gas, which is discharged without introducing other impurity ions into the system, thus producing high-purity manganese chloride.

5. The method for recovering manganese chloride from a sartan biphenyl catalyst according to claim 1, characterized in that, The specific steps for S4 are as follows: first, add manganese carbonate to the reduced system to neutralize excess hydrochloric acid. The system is then neutralized to a pH of 2-3. Next, add more manganese carbonate to adjust the overall pH to 5-7. Finally, filter to remove trace amounts of insoluble impurities from the system.

6. The method for recovering manganese chloride from a sartan biphenyl catalyst according to claim 1, characterized in that, The specific steps for S5 are distillation to a Baume degree of 52-53. At this concentration, the material will not crystallize at the distillation completion temperature, and the impurities in the crystallized material will not precipitate out together, resulting in a considerable yield.

7. The method for recovering manganese chloride from a sartan biphenyl catalyst according to claim 1, characterized in that, The crystallized filtrate from S6 is distilled under reduced pressure with stirring under vacuum conditions of ≤-0.05MPa, and concentrated to a Baume degree of 52-53. It is then allowed to stand for static crystallization for 3-5 days. The upper mother liquor is returned for re-oxidation, and the lower crystals are dissolved in water and then added to S4 for filtration.

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